The purpose of this proposed research is to investigate the relationship between free radical-induced oxidation and retinal degenerations. Specifically, we will test the hypothesis that certain types of retinal degenerations are caused by products of free radical-induced lipid peroxidation of the long-chain polyunsaturated fatty acids in outer segment membranes. The following objectives will be addressed: (1) To demonstrate specific mechanisms for the generation of oxygen radicals in the retinas. (2) To determine the products of lipid peroxidation present in degenerating retinas. (3) To exsmine the relationship of oxygen radicals and pro-oxidants in the production of functional, structural, and chemical changes in the retina and determine if these alterations can be reduced or prevented when antioxidants or other radical scavengers ar provided prior to the insult. We will use a combination of biochemical, electrophysiological, psychophysical, and micsroscopic analyses to determine causal relationships between lipid peroxides and retinal degenerations in tiddues from human, monkeys, rats, and frogs. These results will be of practical importance in the management of eye disorders that arise secondary to light- or drug-induced formation of lipid peroxides.